mysql - 在目标表具有一对一的情况下使用 hasManyThrough

Question

如果我们取 Laravels example在 hasManyThrough 上并将其更改如下:

countries
    id - integer
    name - string

users
    id - integer
    country_id - integer
    website_id - integer
    name - string

websites
    id - integer
    title - string

以users作为中间关系，我可以在country模型上使用hasManyThrough()来获取websites ？

我尝试了这个，结果出现错误

namespace App;

use Illuminate\Database\Eloquent\Model;

class Country extends Model
{
    /**
     * Get all of the websites for the country.
     */
    public function websites()
    {
        return $this->hasManyThrough('App\Website', 'App\User');
    }
}

Illuminate\Database\QueryException:SQLSTATE[42S22]:未找到列:1054 未知列

也许用户必须拥有许多网站才能实现此功能？

Answer 1

您可以根据 @Samir 的评论更改表结构以匹配 Laravel 的期望，也可以自定义键以匹配现有的表结构。

https://laravel.com/docs/5.8/eloquent-relationships

Typical Eloquent foreign key conventions will be used when performing the relationship's queries. If you would like to customize the keys of the relationship, you may pass them as the third and fourth arguments to the hasManyThrough method. The third argument is the name of the foreign key on the intermediate model. The fourth argument is the name of the foreign key on the final model. The fifth argument is the local key, while the sixth argument is the local key of the intermediate model:

public function websites()
{
    return $this->hasManyThrough('App\Website', 'App\User','country_id','id','website_id','website_id');
}